1. Subphylum Crustaceans
Phylum Arthropoda

2. Characteristics 67,000 species Lobsters, crabs, crayfish, shrimp
Also known as “insects of the sea”
Mainly marine
Only arthropods with two pairs of antennae
Also have one pair of mandibles and two pairs of maxillae
Have a pair of appendages on each body segment
Most have between segments, but some can have as many as 60 or more.

3. Characteristics Three Tagmata:
Head
Thorax
Some crustaceans have fused the head and thoracic segments together to form the Cephalothorax
Abdomen
Some have a carapace-the dorsal cuticle of the head may extend posteriorly and around the sides to cover the abdomen and thoracic segments (ex. a lobster shell)

4. Characteristics
Bodies are covered with a secreted cuticle composed of chitin, protein, and calcareous material
The harder, heavy plates of larger crustaceans contain large portions of calcareous deposits
Provides a hard protective covering
Soft and thin at the joints
Will have a telson, which will bear the anus

5. Muscular System Striated muscles Flexors- draw a part toward the body
Extensors- extend a part outward

6. Circulatory System Open circulatory system
No veins
No separation of blood from interstitial fluid
Hemolymph (blood) enters the dorsal heart (single-chambered sac of striated muscle) from the surrounding hemocoel (space in the coelom containing blood)
The hemolymph will enter sinuses (spaces that serve as veins)
Sinuses contain valves that prevent backflow into the heart
The hemolymph will travel through the sinus to different organs such as the gills for oxygen and carbon dioxide exchange

7. Circulatory System Hemolymph may be colorless, reddish or bluish
Hemocyanin (a copper-containing respiratory pigment) and Hemoglobin (an iron-containing pigment) may be present in the solution.
This helps give the hemolymph the property of clotting, which prevents its loss in minor injuries.

8. Respiratory System Use gills for respiration
Gills- delicate, featherlike projections with a very thin cuticle used for gas exchange

9. Nervous System Have a well developed sense organ Advance eyes
Tactile hairs- cover mouthparts, cuticle and telson
Chemical senses for taste and smell can reside in receptors on antennae, mouthparts etc.

10. Reproduction
Most crustaceans are dioecious

11. Crustacean Evolution

12. Classes Class Remipedia Class Cephalocarida Class Branchiopoda
Class Ostracoda
Class Maxillopoda
Class Malacostraca

13. Class Remipedia Very small class of crustacea Live in caves
25-38 trunk segments
Have swimming appendages

14. Class Cephalocarida Small group- 9 species known 2-3mm long
Live in the bottom sediments of the intertidal zone of coasts
No eyes
No carapace
No abdominal appendages
True hermaphrodites
Unique because they are the only arthropod that discharges both eggs and sperm into a common duct

15. Class Branchiopoda 10,000 species 3 orders:
Anostraca- fairy shrimp
Notostraca- tadpole shrimp
Diplostraca- water fleas
Have phyllopodia – legs that serve as chief respiratory organs
Water fleas (cladocerans) will often produce only females in the summer, by parthenogensis (unisexual reproduction of a female) increasing the population.
When conditions are unfavorable, some males will be produced, and eggs that must be fertilized are produced by normal meiosis
Fertilized eggs are highly resistant to cold weather

16. Class Ostracoda
Enclosed in a bivalved carapace, encloses the body but not the head
Mussel shrimp or seed shrimp
Development is gradual by metamorphosis

17. Class Maxillopoda 6 subclasses: Subclass Mystacocarida
Subclass Copepoda
Subclass Tantulocarida
Subclass Branchiura
Subclass Pentastomida
Subclass Cirripedia

18. Subclass Mystacocarida
Tiny crustaceans
Live in interstitial water between sand grains of marine beaches
Only 10 species

19. Subclass Copepoda Small Lack carapace
Antennules are often longer than other appendages and used for swimming

20. Subclass Tantulocarida
12 species known
No head appendages except for one pair of antennae on sexual females
Parathenogenetic
Lose their abdomen and all thoracic limbs during metamorphosis

21. Subclass Branchiura Small group of fish ectoparasites
Mouthparts are modified for sucking- second maxillae have been modified as suction cups
5-10mm long
Broad shield-like carapace
Unsegmented abdomen
Fish heavily infected with these crustaceans can get infections and die

22. Subclass pentastomida
Tongue worms
130 species
Wormlike parasites of the respiratory system of vertebrates
Adults live mostly in lungs of reptiles (snakes, lizards and crocodiles
Intermediate hosts may consist of fish or other reptiles, sometimes mammals
1-13cm
Females are larger than males
Females may produce several million eggs

23. Subclass Cirripedia Barnacles Enclosed in a shell of calcareous plates
Sessile as adults
No abdomen
Thoracic legs are long
Nonparasitic barnacles are hermaphroditic
Can have bivalve carapace

24. Class Malacostraca 20,000 species Largest class with great diversity
3 subclasses, 14 orders and many suborders
4 orders we will discuss:
Order Isopoda
Order Amphipoda
Order Euphausiacea
Order Decapoda

25. Order Isopoda Truly terrestrial Dorsoventrally flattened
Lack a carapace
Psuedotracheae- abdominal appendages bearing gills
Can roll into tight ball for protection
Ex. Pill bugs (Rolly Pollies)

26. Order Amphipoda Lack carapace Compressed laterally
Appendages can be used for different functions
Ex. One pair used for swimming, one pair for jumping

27. Order Euphausia Krill 90 species 3-6cm long
Most are bioluminescent- contain a photophore organ which will produce light
Food for many whale and fish species

28. Order Decopoda Lobsters, crabs, crayfishes and “true” shrimp
18,000 species
Very diverse order
5 pairs of walking legs
May have first pair of walking legs are modified to form chelae (pinchers)
Economically important because they are used as food.